log0log.c

这是linux下运行的mysql软件包,可用于linux 下安装 php + mysql + apach 的网络配置

/******************************************************
Database log

(c) 1995-1997 Innobase Oy

Created 12/9/1995 Heikki Tuuri
*******************************************************/

#include "log0log.h"

#ifdef UNIV_NONINL
#include "log0log.ic"
#endif

#include "mem0mem.h"
#include "buf0buf.h"
#include "buf0flu.h"
#include "srv0srv.h"
#include "log0recv.h"
#include "fil0fil.h"
#include "dict0boot.h"
#include "srv0srv.h"
#include "srv0start.h"
#include "trx0sys.h"
#include "trx0trx.h"

/*
General philosophy of InnoDB redo-logs:

1) Every change to a contents of a data page must be done
through mtr, which in mtr_commit() writes log records
to the InnoDB redo log.

2) Normally these changes are performed using a mlog_write_ulint()
or similar function.

3) In some page level operations only a code number of a 
c-function and its parameters are written to the log to 
reduce the size of the log.

  3a) You should not add parameters to these kind of functions
  (e.g. trx_undo_header_create(), trx_undo_insert_header_reuse())

  3b) You should not add such functionality which either change
  working when compared with the old or are dependent on data
  outside of the page. These kind of functions should implement
  self-contained page transformation and it should be unchanged
  if you don't have very essential reasons to change log
  semantics or format.

*/

/* Current free limit of space 0; protected by the log sys mutex; 0 means
uninitialized */
ulint	log_fsp_current_free_limit		= 0;

/* Global log system variable */
log_t*	log_sys	= NULL;

#ifdef UNIV_DEBUG
ibool	log_do_write = TRUE;

ibool	log_debug_writes = FALSE;
#endif /* UNIV_DEBUG */

/* These control how often we print warnings if the last checkpoint is too
old */
ibool	log_has_printed_chkp_warning = FALSE;
time_t	log_last_warning_time;

#ifdef UNIV_LOG_ARCHIVE
/* Pointer to this variable is used as the i/o-message when we do i/o to an
archive */
byte	log_archive_io;
#endif /* UNIV_LOG_ARCHIVE */

/* A margin for free space in the log buffer before a log entry is catenated */
#define LOG_BUF_WRITE_MARGIN 	(4 * OS_FILE_LOG_BLOCK_SIZE)

/* Margins for free space in the log buffer after a log entry is catenated */
#define LOG_BUF_FLUSH_RATIO	2
#define LOG_BUF_FLUSH_MARGIN	(LOG_BUF_WRITE_MARGIN + 4 * UNIV_PAGE_SIZE)

/* Margin for the free space in the smallest log group, before a new query
step which modifies the database, is started */

#define LOG_CHECKPOINT_FREE_PER_THREAD	(4 * UNIV_PAGE_SIZE)
#define LOG_CHECKPOINT_EXTRA_FREE	(8 * UNIV_PAGE_SIZE)

/* This parameter controls asynchronous making of a new checkpoint; the value
should be bigger than LOG_POOL_PREFLUSH_RATIO_SYNC */

#define LOG_POOL_CHECKPOINT_RATIO_ASYNC	32

/* This parameter controls synchronous preflushing of modified buffer pages */
#define LOG_POOL_PREFLUSH_RATIO_SYNC	16

/* The same ratio for asynchronous preflushing; this value should be less than
the previous */
#define LOG_POOL_PREFLUSH_RATIO_ASYNC	8

/* Extra margin, in addition to one log file, used in archiving */
#define LOG_ARCHIVE_EXTRA_MARGIN	(4 * UNIV_PAGE_SIZE)

/* This parameter controls asynchronous writing to the archive */
#define LOG_ARCHIVE_RATIO_ASYNC		16

/* Codes used in unlocking flush latches */
#define LOG_UNLOCK_NONE_FLUSHED_LOCK	1
#define LOG_UNLOCK_FLUSH_LOCK		2

/* States of an archiving operation */
#define	LOG_ARCHIVE_READ	1
#define	LOG_ARCHIVE_WRITE	2

/**********************************************************
Completes a checkpoint write i/o to a log file. */
static
void
log_io_complete_checkpoint(void);
/*============================*/
#ifdef UNIV_LOG_ARCHIVE
/**********************************************************
Completes an archiving i/o. */
static
void
log_io_complete_archive(void);
/*=========================*/
#endif /* UNIV_LOG_ARCHIVE */

/********************************************************************
Sets the global variable log_fsp_current_free_limit. Also makes a checkpoint,
so that we know that the limit has been written to a log checkpoint field
on disk. */

void
log_fsp_current_free_limit_set_and_checkpoint(
/*==========================================*/
	ulint	limit)	/* in: limit to set */
{
	ibool	success;

	mutex_enter(&(log_sys->mutex));

	log_fsp_current_free_limit = limit;

	mutex_exit(&(log_sys->mutex));

	/* Try to make a synchronous checkpoint */
	
	success = FALSE;

	while (!success) {
		success = log_checkpoint(TRUE, TRUE);
	}
}

/********************************************************************
Returns the oldest modified block lsn in the pool, or log_sys->lsn if none
exists. */
static
dulint
log_buf_pool_get_oldest_modification(void)
/*======================================*/
{
	dulint	lsn;

#ifdef UNIV_SYNC_DEBUG
	ut_ad(mutex_own(&(log_sys->mutex)));
#endif /* UNIV_SYNC_DEBUG */

	lsn = buf_pool_get_oldest_modification();

	if (ut_dulint_is_zero(lsn)) {

		lsn = log_sys->lsn;
	}

	return(lsn);
}

/****************************************************************
Opens the log for log_write_low. The log must be closed with log_close and
released with log_release. */

dulint
log_reserve_and_open(
/*=================*/
			/* out: start lsn of the log record */
	ulint	len)	/* in: length of data to be catenated */
{
	log_t*	log			= log_sys;
	ulint	len_upper_limit;
#ifdef UNIV_LOG_ARCHIVE
	ulint	archived_lsn_age;
	ulint	dummy;
#endif /* UNIV_LOG_ARCHIVE */
#ifdef UNIV_DEBUG
	ulint	count			= 0;
#endif /* UNIV_DEBUG */

	ut_a(len < log->buf_size / 2);
loop:
	mutex_enter(&(log->mutex));
	
	/* Calculate an upper limit for the space the string may take in the
	log buffer */

	len_upper_limit = LOG_BUF_WRITE_MARGIN + (5 * len) / 4;

	if (log->buf_free + len_upper_limit > log->buf_size) {

		mutex_exit(&(log->mutex));

		/* Not enough free space, do a syncronous flush of the log
		buffer */

		log_buffer_flush_to_disk();

                srv_log_waits++;

		ut_ad(++count < 50);

		goto loop;
	}

#ifdef UNIV_LOG_ARCHIVE
	if (log->archiving_state != LOG_ARCH_OFF) {
	
		archived_lsn_age = ut_dulint_minus(log->lsn,
							log->archived_lsn);
		if (archived_lsn_age + len_upper_limit
						> log->max_archived_lsn_age) {
			/* Not enough free archived space in log groups: do a
			synchronous archive write batch: */
	
			mutex_exit(&(log->mutex));
	
			ut_ad(len_upper_limit <= log->max_archived_lsn_age);
	
			log_archive_do(TRUE, &dummy);
	
			ut_ad(++count < 50);
	
			goto loop;
		}
	}
#endif /* UNIV_LOG_ARCHIVE */

#ifdef UNIV_LOG_DEBUG
	log->old_buf_free = log->buf_free;
	log->old_lsn = log->lsn;
#endif	
	return(log->lsn);
}

/****************************************************************
Writes to the log the string given. It is assumed that the caller holds the
log mutex. */

void
log_write_low(
/*==========*/
	byte*	str,		/* in: string */
	ulint	str_len)	/* in: string length */
{
	log_t*	log	= log_sys;
	ulint	len;
	ulint	data_len;
	byte*	log_block;

#ifdef UNIV_SYNC_DEBUG
	ut_ad(mutex_own(&(log->mutex)));
#endif /* UNIV_SYNC_DEBUG */
part_loop:
	/* Calculate a part length */

	data_len = (log->buf_free % OS_FILE_LOG_BLOCK_SIZE) + str_len;

	if (data_len <= OS_FILE_LOG_BLOCK_SIZE - LOG_BLOCK_TRL_SIZE) {

	    	/* The string fits within the current log block */
	    
	    	len = str_len;
	} else {
		data_len = OS_FILE_LOG_BLOCK_SIZE - LOG_BLOCK_TRL_SIZE;
		
	    	len = OS_FILE_LOG_BLOCK_SIZE
			- (log->buf_free % OS_FILE_LOG_BLOCK_SIZE)
	    		- LOG_BLOCK_TRL_SIZE;
	}

	ut_memcpy(log->buf + log->buf_free, str, len);

	str_len -= len;
	str = str + len;

	log_block = ut_align_down(log->buf + log->buf_free,
						OS_FILE_LOG_BLOCK_SIZE);
	log_block_set_data_len(log_block, data_len);

	if (data_len == OS_FILE_LOG_BLOCK_SIZE - LOG_BLOCK_TRL_SIZE) {
		/* This block became full */
		log_block_set_data_len(log_block, OS_FILE_LOG_BLOCK_SIZE);
		log_block_set_checkpoint_no(log_block,
						log_sys->next_checkpoint_no);
		len += LOG_BLOCK_HDR_SIZE + LOG_BLOCK_TRL_SIZE;

		log->lsn = ut_dulint_add(log->lsn, len);

		/* Initialize the next block header */
		log_block_init(log_block + OS_FILE_LOG_BLOCK_SIZE, log->lsn);
	} else {
		log->lsn = ut_dulint_add(log->lsn, len);
	}

	log->buf_free += len;

	ut_ad(log->buf_free <= log->buf_size);

	if (str_len > 0) {
		goto part_loop;
	}
        
        srv_log_write_requests++;
}

/****************************************************************
Closes the log. */

dulint
log_close(void)
/*===========*/
			/* out: lsn */
{
	byte*	log_block;
	ulint	first_rec_group;
	dulint	oldest_lsn;
	dulint	lsn;
	log_t*	log	= log_sys;
	ulint	checkpoint_age;

#ifdef UNIV_SYNC_DEBUG
	ut_ad(mutex_own(&(log->mutex)));
#endif /* UNIV_SYNC_DEBUG */

	lsn = log->lsn;
	
	log_block = ut_align_down(log->buf + log->buf_free,
						OS_FILE_LOG_BLOCK_SIZE);
	first_rec_group = log_block_get_first_rec_group(log_block);

	if (first_rec_group == 0) {
		/* We initialized a new log block which was not written
		full by the current mtr: the next mtr log record group
		will start within this block at the offset data_len */

		log_block_set_first_rec_group(log_block,
			 		log_block_get_data_len(log_block));
	}

	if (log->buf_free > log->max_buf_free) {

		log->check_flush_or_checkpoint = TRUE;
	}

	checkpoint_age = ut_dulint_minus(lsn, log->last_checkpoint_lsn);

	if (checkpoint_age >= log->log_group_capacity) {
		/* TODO: split btr_store_big_rec_extern_fields() into small
		steps so that we can release all latches in the middle, and
		call log_free_check() to ensure we never write over log written
		after the latest checkpoint. In principle, we should split all
		big_rec operations, but other operations are smaller. */

		if (!log_has_printed_chkp_warning
		    || difftime(time(NULL), log_last_warning_time) > 15) {

		        log_has_printed_chkp_warning = TRUE;
			log_last_warning_time = time(NULL);
			
		        ut_print_timestamp(stderr);
			fprintf(stderr,
"  InnoDB: ERROR: the age of the last checkpoint is %lu,\n"
"InnoDB: which exceeds the log group capacity %lu.\n"
"InnoDB: If you are using big BLOB or TEXT rows, you must set the\n"
"InnoDB: combined size of log files at least 10 times bigger than the\n"
"InnoDB: largest such row.\n",
				(ulong) checkpoint_age,
				(ulong) log->log_group_capacity);
		}
	}

	if (checkpoint_age <= log->max_modified_age_async) {

		goto function_exit;
	}

	oldest_lsn = buf_pool_get_oldest_modification();

	if (ut_dulint_is_zero(oldest_lsn)
	    || (ut_dulint_minus(lsn, oldest_lsn)
					> log->max_modified_age_async)
	    || checkpoint_age > log->max_checkpoint_age_async) {

		log->check_flush_or_checkpoint = TRUE;
	}
function_exit:

#ifdef UNIV_LOG_DEBUG
	log_check_log_recs(log->buf + log->old_buf_free,
			log->buf_free - log->old_buf_free, log->old_lsn);
#endif

	return(lsn);
}

#ifdef UNIV_LOG_ARCHIVE
/**********************************************************
Pads the current log block full with dummy log records. Used in producing
consistent archived log files. */
static
void
log_pad_current_log_block(void)
/*===========================*/
{
	byte	b		= MLOG_DUMMY_RECORD;
	ulint	pad_length;
	ulint	i;
	dulint	lsn;
	
	/* We retrieve lsn only because otherwise gcc crashed on HP-UX */
	lsn = log_reserve_and_open(OS_FILE_LOG_BLOCK_SIZE);

	pad_length = OS_FILE_LOG_BLOCK_SIZE
			- (log_sys->buf_free % OS_FILE_LOG_BLOCK_SIZE)
			- LOG_BLOCK_TRL_SIZE;

	for (i = 0; i < pad_length; i++) {
		log_write_low(&b, 1);
	}

	lsn = log_sys->lsn;
		
	log_close();
	log_release();

	ut_a((ut_dulint_get_low(lsn) % OS_FILE_LOG_BLOCK_SIZE)
						== LOG_BLOCK_HDR_SIZE);
}
#endif /* UNIV_LOG_ARCHIVE */

/**********************************************************
Calculates the data capacity of a log group, when the log file headers are not
included. */

ulint
log_group_get_capacity(
/*===================*/
				/* out: capacity in bytes */
	log_group_t*	group)	/* in: log group */
{
#ifdef UNIV_SYNC_DEBUG
	ut_ad(mutex_own(&(log_sys->mutex)));
#endif /* UNIV_SYNC_DEBUG */

	return((group->file_size - LOG_FILE_HDR_SIZE) * group->n_files); 
}

/**********************************************************
Calculates the offset within a log group, when the log file headers are not
included. */
UNIV_INLINE
ulint
log_group_calc_size_offset(
/*=======================*/
				/* out: size offset (<= offset) */
	ulint		offset,	/* in: real offset within the log group */
	log_group_t*	group)	/* in: log group */
{
#ifdef UNIV_SYNC_DEBUG
	ut_ad(mutex_own(&(log_sys->mutex)));
#endif /* UNIV_SYNC_DEBUG */

	return(offset - LOG_FILE_HDR_SIZE * (1 + offset / group->file_size));
}

/**********************************************************
Calculates the offset within a log group, when the log file headers are
included. */
UNIV_INLINE
ulint
log_group_calc_real_offset(
/*=======================*/
				/* out: real offset (>= offset) */
	ulint		offset,	/* in: size offset within the log group */